# US 12,184,058 B2 · Protection circuit, battery pack, and protection circuit operating method

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- Number: US 12,184,058 B2
- Document ID: US12184058B2
- Status: Granted
- Kind: B2
- Application number: 17/755,371
- Filed: 2020-11-09
- Published: 2022-12-22
- Granted: 2024-12-31
- Earliest claimed: 2019-11-08
- Assignees: Dexerials Corporation
- Applicants: Dexerials Corporation
- Inventors: Yuji Furuuchi; Chisato Komori
- Web page: https://patentgrep.com/patent/US12184058B2

## CPC

- H02H 7/18: for batteries; for accumulators
- H01H 37/76: Contact member actuated by melting of fusible material, actuated due to burning of combustible material or due to explosion of explosive material
- H01M 10/44: Methods for charging or discharging (circuits for charging H02J7/00)
- H02H 1/0007: {concerning the detecting means (in general G01R or other subclasses of G01; reed switches H01H71/2445)}
- H02H 3/085: {making use of a thermal sensor, e.g. thermistor, heated by the excess current (also responsive to the temperature of the protected device H02H5/041, thermal images H02H6/00)}
- H02H 3/087: for DC applications
- H02J 7/62: against overcurrent
- H02H 3/05: with means for increasing reliability, e.g. redundancy arrangements {(for logic circuits H03K19/003)}
- Y02E 60/10: Energy storage using batteries
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00)
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided is a protection circuit capable of reliably preventing an overcurrent or a sneak current after cutoff to improve safety, implementing cost reduction with a device configuration simpler than conventional device configurations, and further reducing a failure rate of a device. In a protection circuit, after one of two fuse elements provided in each of a plurality of protection elements is blown due to an overcurrent flowing along a current-carrying path, a heater provided in at least one of the plurality of protection elements generates heat due to a sneak current flowing via the plurality of protection elements on the current-carrying path which is remained and blows the other of the two fuse elements provided in the at least one of the plurality of protection elements.

## Claims

### Claim 1

A protection circuit comprising:
a plurality of protection elements connected in parallel on a current-carrying path between a battery and an external circuit,
wherein each of the plurality of the protection elements has two fuse elements connected in series on the current-carrying path and a heater configured to blow the fuse elements in a current-carrying process, and
wherein, after one of the two fuse elements provided in each of the plurality of protection elements is blown due to an overcurrent flowing along the current-carrying path, the heater provided in at least one of the plurality of protection elements generates heat due to a sneak current flowing via the plurality of protection elements on the current-carrying path which is remained, in order to blow the other of the two fuse elements provided in the at least one of the plurality of protection elements.

### Claim 2 (depends on 1)

The protection circuit according to claim 1, wherein power higher than or equal to operating power of the plurality of the protection elements is applied to the heater provided in at least one of the plurality of protection elements on the current-carrying path, which is remained, according to the sneak current flowing along the current-carrying path which is remained.

### Claim 3 (depends on 1)

The protection circuit according to claim 1, wherein a lower limit value of operating power of the plurality of the protection elements is set to a value of power lower than or equal to power calculated on the basis of a voltage of the battery and resistance including composite resistance of a plurality of heaters on the current-carrying path which is remained.

### Claim 4 (depends on 3)

The protection circuit according to claim 3,
wherein the voltage of the battery has a lower limit value of a voltage range of the battery,
wherein the composite resistance of the plurality of heaters is calculated from a lower limit value and an upper limit value of resistance tolerance of the heater, and
wherein the lower limit value of the operating power of the plurality of the protection element is calculated from a lower limit value of a voltage range in a charging/discharging process of the battery and the lower limit value and the upper limit value of the resistance tolerance of the heater.

### Claim 5 (depends on 4)

The protection circuit according to claim 4,
wherein an equivalent circuit in which two resistors connected in parallel and one resistor are connected in series is used,
wherein the lower limit value of the voltage range in the charging/discharging process of the battery is set for a voltage applied to both ends of the equivalent circuit,
wherein the lower limit value of the resistance tolerance of the heater is set as a resistance value of the one resistor,
wherein the upper limit value of the resistance tolerance of the heater is set as a resistance value of the two resistors, and
wherein power calculated on the basis of the voltage applied to both ends of the equivalent circuit and composite resistance of the two resistors and the one resistor is set so that the power is greater than or equal to the lower limit value of the operating power of the protection element.

### Claim 6 (depends on 1)

The protection circuit according to claim 1, further comprising:
a first fuse element and a second fuse element connected in series;
a first electrode unit connected to the first fuse element on a side opposite to the second fuse element;
a second electrode unit connected to the second fuse element on a side opposite to the first fuse element;
a third electrode unit connected between the first fuse element and the second fuse element and connected to the heater in series; and
a fourth electrode unit connected to the heater on a side opposite to the third electrode unit.

### Claim 7 (depends on 6)

The protection circuit according to claim 6,
wherein the first fuse element is connected to a side of the battery,
wherein the second fuse element is connected to a side of the external circuit, and
wherein the heater has one end connected to the first fuse element and the second fuse element via the third electrode unit and an other end connected to the battery via the fourth electrode unit.

### Claim 8 (depends on 7)

The protection circuit according to claim 7, further comprising:
a switching element connected between the heater and the battery.

### Claim 9 (depends on 1)

A battery pack comprising:
the protection circuit according to claim 1.

### Claim 10 (depends on 1)

The protection circuit according to claim 1, wherein each of the plurality of protection elements has a path along which the sneak current flows and the path is the current-carrying path which remains.

### Claim 11

A method of operating a protection circuit including a plurality of protection elements connected in parallel on a current-carrying path between a battery and an external circuit, the method comprising:
after one of two fuse elements provided in each of the plurality of protection elements is blown due to an overcurrent flowing along the current-carrying path, generating heat on a heater provided in at least one of the plurality of protection elements, due to a sneak current flowing via the plurality of protection elements on the current-carrying path which is remained and blowing an other of the two fuse elements provided in the at least one of the plurality of protection elements.